/**********************************************************
  * 参数说明：
  * number：要格式化的数字
  * decimals：保留几位小数
  * dec_point：小数点符号
  * thousands_sep：千分位符号
  * roundtag:舍入参数，默认 "ceil" 向上取,"floor"向下取,"round" 四舍五入
  *
  * Example:: 
  *console.log(number_format(2, 2, ".", ","))//"2.00"
    console.log(number_format(3.7, 2, ".", ","))//"3.70"
    console.log(number_format(3, 0, ".", ",")) //"3"
    console.log(number_format(9.0312, 2, ".", ","))//"9.03"
    console.log(number_format(9.00, 2, ".", ","))//"9.00"
    console.log(number_format(39.715001, 2, ".", ",", "floor")) //"39.71"
    console.log(number_format(9.7, 2, ".", ","))//"9.70"
    console.log(number_format(39.7, 2, ".", ","))//"39.70"
    console.log(number_format(9.70001, 2, ".", ","))//"9.71"
    console.log(number_format(39.70001, 2, ".", ","))//"39.71"
    console.log(number_format(9996.03, 2, ".", ","))//"9996.03"
    console.log(number_format(1.797, 3, ".", ",", "floor"))//"1.797"
  **/
export function number_format(number, decimals, dec_point, thousands_sep,roundtag) {
 
  number = (number + '').replace(/[^0-9+-Ee.]/g, '')
  roundtag = roundtag || 'ceil' //"ceil","floor","round"
  let n = !isFinite(+number) ? 0 : +number,
    prec = !isFinite(+decimals) ? 0 : Math.abs(decimals),
    sep = (typeof thousands_sep === 'undefined') ? ',' : thousands_sep,
    dec = (typeof dec_point === 'undefined') ? '.' : dec_point,
    s = '',
    toFixedFix = function (n, prec) {
 
      let k = Math.pow(10, prec)
      console.log()
 
      return '' + parseFloat(Math[roundtag](parseFloat((n * k).toFixed(prec*2))).toFixed(prec*2)) / k
    }
  s = (prec ? toFixedFix(n, prec) : '' + Math.round(n)).split('.')
  let re = /(-?\d+)(\d{3})/
  while (re.test(s[0])) {
    s[0] = s[0].replace(re, '$1' + sep + '$2')
  }
 
  if ((s[1] || '').length < prec) {
    s[1] = s[1] || ''
    s[1] += new Array(prec - s[1].length + 1).join('0')
  }
  return s.join(dec)
}